Summary The goal of this project is to elucidate basic mechanisms of eukaryotic translation initiation using structural and other biochemical methods. Eukaryotic translation initiation is highly regulated by elements of the untranslated regions of mRNAs, 5'UTR and 3'UTR, by the cellular concentration of initiation factors, by the action of regulatory proteins and by signaling pathways that are initiated by external messages or cellular events. Dysregulation of translation initiation by elevated levels of initiation factors is found in many forms of cancer. Thus, correcting for out-of-balance initiation with small molecule agents is a promising new route for cancer therapy. The proposed research is focused on the mechanisms by which the small ribosomal particle is recruited to mRNA, mediated by the initiation factors eIF4E, eIF4G and the regulatory phosphoprotein 4EBP-1. The second aspect is focused on scanning of the pre-initiation complex to the AUG initiation codon, aided by the interplay between the initiation factors eIF4A, eIF4G and eIF4H. The third topic is on elucidating the interaction of the Mnk1/2 kinases with the HEAT3 domain of eIF4G and its role in phosphorylating eIF4E, which has been related to metastasis. A significant aspect is to discover and characterize inhibitors of initiation with the goal of developing anti-cancer agents with broad specificity. The research will pursue three specific aims: 1. Regulation of the eIF4E/eIF4G interaction by 4EBP proteins and inhibitors 2. Analyze and target the eIF4G interactions with eIF4A, RNA and eIF4H. 3. Inhibit eIF4G-MNK1/2 interaction to prevent eIF4E phosphorylation and cancer metastases.